Historically, a cavity in a vital tooth has been filled using either a gold filling or an amalgam of silver and mercury. Concern over the potential health hazard from the use of mercury in dental fillings has created a need for a substitute dental filling material and/or method for filling teeth using a filling material which does not contain mercury. Ceramic materials and composites have been investigated and are, to a limited extent, currently used as a substitute for the mercury amalgam. The ceramic materials do not, however, form as durable or as strong a filling in comparison to a mercury amalgam or a gold-based metal filling. For larger cavities, an inlay, partial veneer or full veneer is usually indicated, and is almost exclusively fabricated with metal. At present, the inlay preparation requires laboratory involvement similar to the effort and expense in making a full crown.
The procedure currently practiced for preparing an inlay, onlay, or veneer requires careful cavity preparation, followed by taking an impression of the cavity which is then forwarded to a dental laboratory to prepare a casting in much the same manner as in the preparation of a full crown. The inlay or onlay may also result in an unsightly exhibition of metal since it is difficult to form a coating of porcelain for application to only a specific area or surface. Moreover, the inlay may fit poorly if the casting does not accurately reproduce the anatomical contour of the cavity.